Coronary bypass surgery is a frequently performed cardiac surgery. Approximately 320,000 patients undergo this procedure each year in the U.S. alone. Coronary artery bypass surgery is a technically delicate procedure, and surgeons routinely sew saphenous vein grafts or internal mammary arteries onto coronary arteries as small as one millimeter in diameter. Microsurgical instruments, optical magnification, very fine sutures and fine needles are all necessary to obtain the required precision. In a large majority of procedures the patient is placed on cardiopulmonary bypass as part of the operative procedure. Following commencement of cardiopulmonary bypass, the heart is arrested by the infusion of a cold cardioplegia solution into the coronary arteries and veins. By these means the surgeon is able to operate on a flaccid and motionless heart. Some surgeons have attempted to carry out bypass grafting on the beating heart, but the accuracy and delicacy of correct suture placement coupled with the increased operative time is such that it is difficult to routinely use this technique.
In most patients there is no medical reason to place patients on cardiopulmonary bypass, except to render the heart immobile so that the bypass graft can more easily be sewn onto the effected coronary artery.
Cardiopulmonary bypass is an expensive and complicated procedure in terms of drug therapy, personnel, equipment and prolonged operation time. It produces metabolic, hematologic and other disturbances to the patient, as well as requiring that the patient receive anticoagulation therapy during the bypass procedure, and reversal of anticoagulant following the cessation of cardiopulmonary bypass. Because of the residual volume of the cardiopulmonary bypass circuit, and the because the patient is anticoagulated, many patients have to receive blood transfusions during or following open heart surgery. Thus, the use of cardiopulmonary bypass has many drawbacks.
The present invention addresses the problems faced in coronary bypass surgery that arise from the need for cardiopulmonary bypass.